Microbially mediated deposition of postglacial transition layers from the Neoproterozoic Otavi Group, Namibia: evidence of rapid deglaciation after the Sturtian cryogenic period
Year: 2015
Type: article
Abstract: Iron-rich postglacial transition layers from early Cryogenian "Snowball Earth" sedimentary environments of the Otavi Group (Namibia) were studied by microtextural high-resolution mineralogical and geochemical methods.Series of Fe-rich biomats (goethite, hematite) were identified, and signs of diverse microbial, filamentous Fe-oxidizing, and cyanobacterial activity were documented for the first time.The matrix mineralogy consists of quartz and dolomite, diverse organic matter, muscovite, apatite, and pyrite.On the basis of mineralized bacterial layering of the Fe-rich biomats, the postglacial transition layers are interpreted to have formed within a few hundred years under suboxic, neutrophilic, shallow, fresh-to brackish-water conditions during an initial rapid deglaciation process from a Neoproterozoic "Snowball Earth" environment.Thus we suggest that the overlying Rasthof cap carbonates, influenced by tectonic subsidence of the region, may also have been deposited within a very short period, comprising the entire deglaciation process.
Authors: Gyollai Ildikó, Polgári Márta Piroska, Fintor Krisztián, Popp Friedrich, Mader Dieter, Pál-Molnár Elemér, Nagy Szabolcs, Koeberl Christian
Language: English
Subfield: Paleontology
Field: Earth and Planetary Sciences
Domain: Physical Sciences
Open Access status: green
OpenAlex ID: W408146725